Entomology (Study of Bugs)/Hawkmoth / Sphinx caterpillar?

Hi - I'd be very grateful for help in identifying this caterpillar, found crawling across a sand dune leaving these distinctive tracks, in the Outer Banks, North Carolina. Seen August 18. Thank you

AnswerTom:

I am sorry, but I am not very good with caterpillars. From the looks of it, it is *not* a sphinx moth caterpillar. Not all of them have a horn on the rear end, but this one does not seem to fit with those that don't.

Expertise

I answer insect and spider identification questions ONLY. Attach images if possible. No "what bit me?", "what do I feed this bug in captivity?", or science fair project questions please. NO TECHNICAL QUESTIONS ABOUT INSECT PHYSIOLOGY.

Experience

Principal author, Kaufman Field Guide to Insects of North America. Professional entomologist employed previously at University of Massachusetts, Chase Studio, Inc., and Cincinnati Zoo; contract work for West Virginia Department of Natural Resources, Smithsonian Institution, and Portland (Oregon) State University.

PublicationsAuthor, Kaufman Field Guide to Insects of North America, Missouri Conservationist magazine, Ranger Rick, Birds & Blooms, Timeline (journal of the Ohio Historical Society). I have contributed to several books as well.

Education/CredentialsOregon State University, undergraduate major in entomology, did not receive degree.

Awards and HonorsOne of the top 50 experts in all categories for AllExperts.com, 2009.